Microphase-engineered ether-free proton exchange membranes for high-performance water electrolysis

A series of ether-free sulfonated poly(biphenyl-piperidine-hexylene)-co-poly(biphenyl-trifluoroacetophenone) (SPBPH-TFP-x) proton exchange membranes was developed via an amine-alkylation strategy. Flexible hexylene-tethered sulfonic acid side chains were introduced onto rigid aromatic backbones through piperidine linkers, promoting distinct microphase separation and continuous proton-conducting channels. Among the prepared membranes, SPBPH-TFP-70 exhibited a high proton conductivity of 0.107 S cm-1 and a tensile strength of 83.5 MPa at room temperature. The membrane also showed excellent oxidative stability, retaining over 87.5% of its initial mass after 15 h in Fenton’s reagent at 80 oC. Owing to its balanced conductivity and durability, SPBPH-TFP-70 delivered outstanding proton exchange membrane water electrolysis performance, achieving a current density of 6.13 A cm-2 at 2.0 V and 90 oC using Pt/C catalysts. These results demonstrate the promise of SPBPH-TFP-70 as a high-performance proton exchange membrane for efficient hydrogen production.